Database Link Notes with a Target Oracle AI Database

Provides notes for creating database links to a target Oracle AI Database (when the target is not an Autonomous AI Database)

Notes for database links to other Oracle AI Databases:

• If you are using database links between Autonomous AI Database and other Oracle AI Databases, you might need to apply Patch 33843368 on the Oracle AI Database that is not an Autonomous AI Database. This applies to cases where the Autonomous AI Database instance is either the source or the target of the database link.

  See My Oracle Support Knowledge Base: Patch Requirement For Database Links Between ADB-S And Other Oracle AI Databases(Doc ID 2874244.1) for further details.

• Only one wallet file is valid per directory for use with database links. You can only upload one cwallet.sso at a time to the directory you choose for wallet files (for example DBLINK_WALLET_DIR). This means with a cwallet.sso in DBLINK_WALLET_DIR you can only create database links to the databases for which the wallet in that directory is valid. To use multiple cwallet.sso files with database links you need to create additional directories and put each cwallet.sso in a different directory. When you create database links with DBMS_CLOUD_ADMIN.CREATE_DATABASE_LINK, specify the directory that contains the wallet with the directory_name parameter.

  See Create Directory in Autonomous AI Database for information on creating directories.

• Supported target Oracle AI Database versions for database links to another Oracle AI Database are: 19c, 12.2.0, and 12.1.0.

  Note: For complete information on supported versions, see Client Server Interoperability Support Matrix for Different Oracle Versions (Doc ID 207303.1)

• Autonomous AI Database sets the SEC_CASE_SENSITIVE_LOGON parameter to true and this value cannot be changed. If your target database is not an Autonomous AI Database, then you must set SEC_CASE_SENSITIVE_LOGON parameter to true on the target database. If SEC_CASE_SENSITIVE_LOGON is set to false on the target database, then error ORA-28040: No matching authentication protocol is raised.

• To list the database links, use the ALL_DB_LINKS view. See ALL_DB_LINKS for more information.

• The wallet file, along with the Database user ID and password provide access to data in the target Oracle AI Database. Store wallet files in a secure location. Share wallet files only with authorized users.

• When the Autonomous AI Database instance is on a private endpoint, there are two options to specify the target database: use either the hostname parameter or the rac_hostnames parameter:

  • For a target on a private endpoint, DBMS_CLOUD_ADMIN.CREATE_DATABASE_LINK supports specifying a single hostname with the hostname parameter. On a private endpoint, using an IP address, SCAN IP, or a SCAN hostname is not supported (when the target is on a public endpoint, CREATE_DATABASE_LINK supports using an IP address, a SCAN IP, or a SCAN hostname).

  • When the target is an Oracle RAC database, use the rac_hostnames parameter to specify one or more hostnames with DBMS_CLOUD_ADMIN.CREATE_DATABASE_LINK. This allows you to take advantage of the high availability capabilities of Oracle RAC. Using an IP address, a SCAN IP, or a SCAN hostname in the rac_hostnames value is not supported.

    When you specify a list of host names in the rac_hostnames parameter, CREATE_DATABASE_LINK uses all of the specified host names as addresses in the connect string. If one of the specified hosts is not available on the target Oracle RAC database, Autonomous AI Database automatically attempts to connect using another host name from the list.

  • DBMS_CLOUD_ADMIN.CREATE_DATABASE_LINK does not support a value of localhost for the hostname or in the rac_hostnames parameter.

• When private_target => TRUE, creating cross-realm database links, where the source database and the target database are in different Oracle Cloud Infrastructure realms, is not supported.